9/3/2013 JOINTS. Joints. Axial Skeleton STRUCTURE AND FUNCTION:

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1 STRUCTURE AND FUNCTION: JOINTS Joints A connection between 2 or more bones A pivot point for bony motion The features of the joint help determine The ROM freedom Functional potential of the joint Axial Skeleton The Axial Skeleton makes up the central bony axis of the body and is composed of: the skull hyoid bone sternum ribs vertebral column sacrum coccyx 1

2 Appendicular Skeleton Just as the name suggests, the appendicular skeleton is composed of the appendages or extremities: This includes the supporting structures ANATOMY & FUNCTION BONE Primary Types of Tissue Cortical (compact) outmost portions of bone Strong Dense Absorptive (forces) Cancellous (spongy) inner portions of bone Porous Lightens the bone Redistributes forces & is covered by articular cartilage 2

3 Cancellous bone Hip bone Hip bone Structural Features of Bone Diaphysis Epiphyses (2) Proximal Distal Articular cartilage hyaline cartilage Periosteum Medullary canal Endosteum 3

4 Epiphyseal Plates of knee --growth plates Normal Adult Knee Primary Types of Bones Five categories Long Sesamoid Irregular Flat Short sesamoid Joints A connection between 2 or more bones A pivot point for bony motion The features of the joint help determine The ROM freedom Functional potential of the joint 4

5 Joint Classifications Synarthrosis (Fibrous) Allows little to no movement Sutures in the skull Distal tibiofibular joint Suture lines Joint Classifications Amphiarthrosis Formed by fibro and hyaline cartilage Shock absorbers Allows limited motion Joint Classifications Diarthrosis No direct union between the bone ends Synovial fluid contained within a capsule 5

6 Joint Classifications Diarthrosis (Synovial Joints) Contains fluid-filled cavity between 2 or more bones What Synovial fluid- All synovial joints have 7 common elements Why for joint lubrication & nutrition Articular cartilage- Articular capsule- Synovial membrane- Capsular ligaments- Blood vessels- Sensory nerves- to spread out and absorb forces to contain the joint to produce the fluid for the joint to limit excessive joint motion to provide nutrients, permit healing to occur transmit pain and awareness of position (proprioception) Synovial Joint Classifications The structure of the joint determines the functional potential for the joint. Most of the names intentionally resemble functional structures! Hinge Pivot Ellipsoid Ball-and-Socket Condyloid Saddle Plane Hinge Joint Primary Motions Examples 1 Flexion and extension Door hinge Humero-ulnar joint, interphalangeal joints 6

7 Pivot Joint Primary Motions Examples 1 Spinning one member on an axis; Rotation Door knob Proximal radioulnar joint Ellipsoid Joint Primary Motions Examples 2 Flex & Ext, ABD & ADD Flattened convex with concave trough Radiocarpal joint Condyloid Joint Primary Motions Example 2 Biplanar Motion Spherical convex surface & concave cup Tibiofemoral joint MCP joint 7

8 Saddle Joints Primary Motions Examples 2 Biplanar, excluding spin Horseback rider on a saddle CMC joint of the thumb Sternoclavicular joint Plane Joints Primary Motions Variable Slide &/or rotation Examples Book sliding or spinning on a table Intercarpal joints intertarsal joints Ball & Socket Joint Primary Motions Examples 3 Flex & Ext, ABD & ADD, IR & ER Spherical convex surface & concave cup Glenohumoral joint and hip 8

9 Joint Positions Close-packed Surfaces of joint matches perfectly Joint stability is greatest Usually at one extreme end range Open-packed All other positions than close packed Usually in the middle of range of motion Connective Tissue All connective tissues that support the joints of the body are composed of: Fibers Type I: thick, resist elongation Primarily compose ligaments Type II: thinner, less stiff Primarily composes hyaline cartilage Elastin: elastic in nature Have more give Ground substance viscous fluid in which the fibers and cells are embedded occupies the space between the cells and fibers of connective tissues Cells Responsible for maintenance & repair 9

10 Types of Connective Tissue in Joints Dense Irregular Connective Tissue Binds bones together Makes up ligaments & external joint capsule Type I collagen Injuries- Ankle sprain Types of Connective Tissue in Joints Articular Cartilage Resists compressive and shear forces in articular surfaces Covers the ends of articulating surfaces of bones in synovial joints High % type II collagen content which helps to anchor the cartilage to the bone Injuries Wear & tear decreases it s effectiveness in reducing compression leading to OA and joint pain & inflammation. Types of Connective Tissue in Joints Fibrocartilage Provides support & stabilization to joints, resists compression & shear forces Makes up the intervertebral discs and menisci of the knees Multidirectional bundles of type I collagen Injuries Tearing can cause disruption of the integrity of the structure and pain with loss of function 10

11 Types of Connective Tissue in Joints Bone Forms primary supporting structure of the body & a rigid level to transmit the force of muscle to move & stabilize the body Forms internal levers of musculoskeletal system Specialized arrangement of Type I collagen & framework for hard mineral salts Injuries osteoporosis Types of Connective tissue 1. Dense irregular (attachment points) a. Ligaments b. Joint capsule 2. Articular cartilage (ease of movement) a. Covering at the end of bones of synovial joints 3. Fibrocartilage (the shock absorbers) a. Menisci pleural of meniscus b. Intervertebral discs 4. Bone (the levers in the musculoskeletal system) 11

12 Tendons versus Ligaments Tendon: attaches muscle to bone Collagen fibers are aligned parallel to one another Ligament: attaches bone to bone Collagen fibers are aligned in irregular crossing patterns 12